The views were not quite so breathtaking as the National Mall in Washington, nor were there any world leaders in attendance, but in the bowels of a New Orleans convention centre Beyoncé nevertheless found a stage from which to answer her critics. Ten days on from her lip-synched performance at the president's inauguration ceremony, the singer treated reporters at a Super Bowl half-time show press conference to a live rendition of The Star-Spangled Banner.

Introduced to the media by an NFL spokesman, Beyoncé invited her audience to stand before launching straight into her a cappella rendition of the US anthem. As she sang, a video board behind the stage displayed the national flag. When she finished, the several hundred journalists filling out Conference Room C at the Ernest N Morial Convention Center responded with an enthusiastic ovation.

Having demonstrated her capacity to perform the song live, Beyoncé then took the opportunity to explain why she had chosen not to in Washington. "I am a perfectionist, and one thing about me, I practice until my feet bleed," she said. "I did not have time to rehearse with the orchestra. It was a live television show and a very, very important emotional show for me. One of my proudest moments.

"Due to the weather, due to the delay, due to no proper sound check, I did not feel comfortable taking a risk. It was about the president and the inauguration, and I wanted to make him and my country proud. So I decided to sing along with my pre-recorded track, which is very common in the music industry, and I'm very proud of my performance."

Half-time show press conferences have a tendency to throw up sympathetic audiences – during an equivalent appearance last year, Madonna was asked by one reporter how she always managed to be so wonderful at everything – but Beyoncé addressed the questions that were put to her eloquently. She explained one of the reasons she had been unable to practice for the inauguration performance had been that she was already devoting much of her time to preparing for the Super Bowl.

Beyoncé acknowledged that she does not spend her Sundays watching the NFL but said that this performance would be an emotional one because of her connection to the area. During Hurricane Katrina in 2005, many families took refuge inside the Superdome, where Sunday's game will take place. "When I was driving up [there], I just got chills because there is so much history," she said. "My family is from Louisiana."

Asked for details on the half-time show itself, Beyoncé refused to say whether she would be joined on stage by her fellow members of Destiny's Child, but did confirm that there would be no lip-syncing this time around. "I will absolutely be singing live. I am well rehearsed and I will absolutely be singing live," she said. "This is what I was born to do. What I'm born for."

More than 112.5 million TV viewers watched last year's Super Bowl half-time show, making it the most-watched musical event of the year in the US. Sunday's edition will be the first to be introduced by fans – with photos submitted by contest winners to be used in the build-up to Beyoncé's appearance.